Does it matter who done it!

In English what is the standard as to word pronunciation?

On RTE's Morning Ireland today an old-hand said 'advertisement', placing the stress on the 'ise'. It sounds horrible. But why?

It's not that long ago that 'sophisticated' people would laugh at such 'mis-pronunciations'.

Before the presidential election one of the candidates said, 'I learned him', another candidate kept confusing the perfect and imperfect tenses.

Does grammar or pronunciation matter?

It seems people are selective when it comes to passing judgement. Oops, is there an 'e' in that word?